Electrical lighting devices of many kinds, shapes and operational principles and capabilities, have gone through various generations of development since Edison's first incandescent electric light bulb. Today it is commonplace to find incandescent, Halogen and compact fluorescent light (“CFL”) bulbs of all forms and shapes, as well as the beginning of a more modern kind of an electric lighting device that is based on light emitting diodes (LEDs). Such modern electric lighting devices can be found, for example, in the form of LED bulbs, LED luminaires, and the like. While the initial cost of such LED electric lighting devices may be higher than some of the other existing lighting solution, these costs may be offset due to the much longer lifetime of LED electric lighting devices and their significantly lower energy consumption costs. In addition, LED-based lighting generally provides better color rendering than CFL bulbs, i.e., a better quality of light, and are more environmentally friendly, both having many recyclable components and lacking the hazardous disposal issues of CFL bulbs.
Prior art LED bulbs and systems, however, tend to be overly complicated and typically incompatible with existing dimmer switches. Some require control methods that are complex, some are difficult to design and implement, and others require many electronic components. A large number of components results in an increased cost and reduced reliability. Many LED drivers utilize a current mode regulator with a ramp compensation in a pulse width modulation (“PWM”) circuit. Other attempts provide solutions outside the original power converter stages, adding additional feedback and other circuits, rendering the LED driver even larger and more complicated.
For example, each individual, typical prior art LED bulb includes, in addition to the LEDs themselves, co-located LED driver circuitry comprising an AC/DC rectifier, a DC/DC converter, a current source, complicated circuitry for analog and PWM dimming, an additional dummy load for compatibility with existing triac-type dimmer switches, and additional feedback circuitry. A typical dummy load and special circuitry is required to support stable operation of a dimmer switch by providing a load to the dimmer during turn on, typically at a frequency of 60 Hz or 120 Hz, and reduces energy conversion efficiency. The significant gap between the high voltages of an input AC voltage and the lower DC voltages required for LEDs needs complex power conversion circuitry which may have as many as forty to seventy components, for example, with additional 10%-15% power losses from the conversion. Also for example, a dimmable LED driver may easily have 30% more circuitry than a nondimmable LED driver, and requires considerably more engineering resources to develop. In addition, a typical triac dimmer presents a comparatively poor interface to an AC line for solid state lighting, corrupting the power factor, introducing additional, nonfundamental harmonics, creating electromagnetic interference (“EMI”) and audio noise problems, and increasing the input RMS current, further requiring corresponding increases in the value of service circuit breakers.
As a consequence, a need remains for a comparatively lower cost solution to provide LED-based lighting, using an apparatus, method and system suitable for replacing the problematic triac dimmer switches and other legacy wall-mounted switches, while simultaneously allowing the use of LED bulbs and luminaires which either utilize new interface standards or are compatible with existing or legacy interface standards, such as typical Edison-based sockets and interfaces, e.g., E12, E14, E26, E27, or GU-10 lighting standards. Such an apparatus, method and system should provide the capability for dimmable LED-based lighting, including remotely controlled dimming and color control, using LED bulbs and luminaires having comparatively few components, allowing lower cost manufacturing and corresponding savings to the consumer. Such an apparatus, method and system should provide comparative ease of use for a consumer, both for installation and bulb replacement.
Such an apparatus, method and system should also provide a wide range of dimming capability (i.e., depth of dimming), and be comparatively simple to implement using comparatively low cost components. Dimming in such lighting system could be executed, for example, by analog or pulse width modulation (“PWM”) light regulation, should be capable of use with different types and qualities of LED bulbs, generally should be free of any significant flicker or other stroboscopic effects, and further should operate without causing electromagnetic interference. Such dimming should also be compatible with typical, widely-used interfaces or controllers. A need remains for an accurate dimming apparatus which provides a considerable depth of dimming, without complicated digital or analog controllers.